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1
Graves, Kynan E., and kgraves@swin edu au. "Electromagnetic energy regenerative vibration damping." Swinburne University of Technology, 2000. http://adt.lib.swin.edu.au./public/adt-VSWT20060307.120939.
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This thesis documents a PhD level research program, undertaken at the Industrial
Institute Swinburne, Swinburne University of Technology between the years of 1997
and 2000. The research program investigated electromagnetic energy regenerative
vibration damping; the process of recovering energy from damped, vibrating systems.
More specifically, the main research objective was to determine the performance of
regenerative damping for the application of vehicle suspension systems. This question
emerged due to the need for continuous improvement of vehicle efficiency and the
potential benefits possible from the development of regenerative vehicle suspension. It
was noted, at the outset of this research, that previous authors had undertaken research
on particular aspects of regenerative damping systems. However in this research, the
objective was to undertake a broader investigation which would serve to provide a
deeper understanding of the key factors.
The evaluation of regenerative vibration damping performance was achieved by
developing a structured research methodology that began with analysing the overall
requirements of regenerative damping and, based on these requirements, investigated
several important design aspects of the system. The specific design aspects included an
investigation of electromagnetic machines for use as regenerative damping devices. This
analysis concentrated on determining the most promising electromagnetic device
construction based on its damping and regeneration properties. The investigation then
proceeded to develop an 'impedance-matching' regenerative interface, in order to control
the energy flows in the system. This form of device had not been previously developed
for electromagnetic vibration damping, and provided a significant advantage in
maximising energy regeneration while maintaining damping control. The results from
this analysis, when combined with the issues of integrating such a system in vehicle
suspension, were then used to estimate the overall performance of regenerative damping
for vehicle suspension systems.
The methodology and findings in this research program provided a number of
contributing elements to the field, and provided an insight into the development of
regenerative vehicle systems. The findings revealed that electromagnetic regenerative
vibration damping may be feasible for applications such as electric vehicles in which
energy efficiency is a primary concern, and may have other applications in similar
vibrating systems.
2
Anasavarapu, Srikantha Phani. "Damping identification in linear vibration." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615994.
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Adhikari, Sondipon. "Damping models for structural vibration." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620975.
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Ganguli, ABHIJIT. "Chatter reduction through active vibration damping." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210980.
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The aim of the thesis is to propose active damping as a potential control strategy for chatter instability in machine tools.The regenerative process theory explains chatter as a closed loop interaction between the structural dynamics and the cutting process. This is considered to be the most dominant reason behind machine tool chatter although other instability causing mechanisms exist.
The stability lobe diagram provides a quantitative idea of the limits of stable machining in terms of two physical parameters: the width of contact between tool and the workpiece, called the width of cut and the speed of rotation of the spindle. It is found that the minimum value of the stability limit is proportional to the structural damping ratio for turning operations. This important finding provides the motivation of influencing the structural dynamics by active damping to enhance stability limits of a machining operation.
A direct implementation of active damping in an industrial environment may be difficult. So an intermediate step of testing the strategy in a laboratory setup, without conducting real cutting is proposed. Two mechatronic "Hardware in the Loop" simulators for chatter in turning and milling are presented, which simulate regenerative chatter experimentally without conducting real cutting tests. A simple cantilever beam, representing the MDOF dynamics of
the machine tool structure constitutes the basic hardware part and the cutting process is simulated in real time on a DSP board. The values of the cutting parameters such as spindle speed and the axial width of cut can be changed on the DSP board and the closed loop interaction between the structure and the cutting process can be led to instability.
The demonstrators are then used as test beds to investigate the efficiency of active damping, as a potential chatter stabilization strategy. Active damping is easy to implement, robust and does not require a very detailed model of the structure for proper functioning, provided a collocated sensor and actuator configuration is followed. The idea of active damping is currently being implemented in the industry in various metal cutting machines as part of the European Union funded SMARTOOL project (www.smartool.org), intended to propose smart chatter control technologies in machining operations.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
5
Ting-Kong, Christopher. "Design of an adaptive dynamic vibration absorber." Title page, contents and abstract only, 1998. http://thesis.library.adelaide.edu.au/adt-SUA/public/adt-SUA20010220.212153.
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Zhu, Jianfeng. "Vibration suppression by using magnetic damping." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440844.
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PENG, WU, and Sebastian Levin. "Chatter Vibration Damping in Parting Tools." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-16798.
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Aumjaud, Pierre. "Vibration damping of lightweight sandwich structures." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/20730.
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Honeycomb-cored sandwich structures are widely used in transport for their high strength-to-mass ratio. Their inherent high stiffness and lightweight properties make them prone to high vibration cycles which can incur deleterious damage to transport vehicles. This PhD thesis investigates the performance of a novel passive damping treatment for honeycomb-cored sandwich structures, namely the Double Shear Lap-Joint (DSLJ) damper. It consists of a passive damping construct which constrains a viscoelastic polymer in shear, thus dissipating vibrational energy. A finite element model of such DSLJ damper inserted in the void of a hexagonal honeycomb cell is proposed and compared against a simplified analytical model. The damping efficiency of the DSLJ damper in sandwich beams and plates is benchmarked against that of the Constrained Layer Damper (CLD), a commonly used passive damping treatment. The DSLJ damper is capable of achieving a higher damping for a smaller additional mass in the host structure compared to the optimised CLD solutions found in the literature. The location and orientation of DSLJ inserts in honeycomb sandwich plates are then optimised with the objective of damping the first two modes using a simple parametric approach. This method is simple and quick but is not robust enough to account for mode veering occurring during the optimisation process. A more complex and computationally demanding evolutionary algorithm is subsequently adopted to identify optimal configurations of DSLJ in honeycomb sandwich plates. Some alterations to the original algorithm are successfully implemented for this optimisation problem in an effort to increase the convergence rate of the optimisation process. The optimised designs identified are manufactured and the modal tests carried out show an acceptable correlation in the trends identified by the numerical simulations, both in terms of damping per added mass and natural frequencies.
9
Ehnes, Charles W. "Damping in stiffener welded structures." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FEhnes.pdf.
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Kidner, Michael Roger Francis. "An active vibration neutraliser." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299609.
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Dickinson, Timothy. "Vibration damping in multispan heat exchanger tubes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/MQ49764.pdf.
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Maheri, M. R. "Vibration damping in composite/honeycomb sandwich beams." Thesis, University of Bristol, 1991. http://hdl.handle.net/1983/d96ba3e9-edb0-4a07-ac6e-69328ed22678.
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GALLUZZI, RENATO. "Vibration Damping Using Electro-Hydrostatic Actuation Technology." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2542506.
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Vibration damping finds its application in almost any system or structure subject to oscillatory excitations. Vehicles, or better, the intrinsic nature of the environments that surround and interact with them demand certain degree of adaptability of the vehicle subsystems to a wide range of working conditions. This requirement, together with the fast development of electronics and motion transducers, leads to the interesting possibility of designing and implementing adaptive damping devices.
In a context where technological alternatives are numerous, the present dissertation explores the potentialities and limitations of the electro-hydrostatic actuation (EHA) technology as a vibration suppression device. For this purpose, the case study of the lead-lag motion damping of a rotorcraft blade is proposed.
Thus, the workflow of the thesis introduces modeling and design aspects that can be applied to any EHA damping application. Considerations about power consumption and technology limitations are covered as well. Then, after a brief introduction to the lead-lag damping phenomenon, the design of the adaptive damper is carried out. This phase yields an off-the-shelf component prototype and a custom EHA damper that integrates all the components in a single manifold. Finally, both devices are tested in an experimental context to assess the validity of the solution for the selected application.
14
Bolter, J. D. "Active damping of framework vibrations." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382018.
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Machado, Luciano G. "Shape memory alloy for vibration isolation and damping." Texas A&M University, 2007. http://hdl.handle.net/1969.1/85772.
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This work investigates the use of shape memory alloys (SMAs) for vibration isolation
and damping of mechanical systems. The first part of this work evaluates the nonlinear
dynamics of a passive vibration isolation and damping (PVID) device through
numerical simulations and experimental correlations. The device, a mass connected
to a frame through two SMA wires, is subjected to a series of continuous acceleration
functions in the form of a sine sweep. Frequency responses and transmissibility of the
device as well as temperature variations of the SMA wires are analyzed for the case
where the SMA wires are pre-strained at 4.0% of their original length. Numerical
simulations of a one-degree of freedom (1-DOF) SMA oscillator are also conducted
to corroborate the experimental results. The configuration of the SMA oscillator is
based on the PVID device. A modified version of the constitutive model proposed
by Boyd and Lagoudas, which considers the thermomechanical coupling, is used to
predict the behavior of the SMA elements of the oscillator.
The second part of this work numerically investigates chaotic responses of a 1-
DOF SMA oscillator composed of a mass and a SMA element. The restitution force
of the oscillator is provided by an SMA element described by a rate-independent,
hysteretic, thermomechanical constitutive model. This model, which is a new version
of the model presented in the first part of this work, allows smooth transitions
between the austenitic and the martensitic phases. Chaotic responses of the SMA oscillator are evaluated through the estimation of the Lyapunov exponents. The Lyapunov
exponent estimation of the SMA system is done by adapting the algorithm
by Wolf and co-workers. The main issue of using this algorithm for nonlinear, rateindependent,
hysteretic systems is related to the procedure of linearization of the
equations of motion. The present work establishes a procedure of linearization that
allows the use of the classical algorithm. Two different modeling cases are considered
for isothermal and non-isothermal heat transfer conditions. The evaluation of
the Lyapunov exponents shows that the proposed procedure is capable of quantifying
chaos in rate-independent, hysteretic dynamical systems.
16
Durfy, Jennifer L. "Investigation of damping treatments for propeller shaft vibration." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0029/MQ65288.pdf.
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Panananda, Nuttarut. "The effects of cubic damping on vibration isolation." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/365357/.
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Vibration isolators are often assumed to possess linear viscous damping which has well known consequences for their performance. However, damping may be designed to be or prove to be nonlinear. This study investigates the effect of cubic damping, as an example of damping nonlinearity, in a single degree of freedom (SDOF) vibration isolation system. The response behaviour due to two excitation types, namely harmonic and broadband excitations, was examined. For harmonic excitation, the Harmonic Balance Method (HBM) was applied to yield approximate closed form solutions and simplified analytical expressions implicitly show the influence of cubic damping for particular frequency regions. The HBM solutions were verified using direct numerical integration. The presence of cubic damping proves to be beneficial for the force excited case. It reduces response amplitude around the resonance frequency and has similar response to an undamped system in the isolation region. In contrast, for base excitation, the cubic damping is detrimental at high excitation frequencies as the base excitation and isolated mass move almost together. The effect becomes more pronounced for larger excitation amplitudes. The case of base excitation was then considered for broadband excitation. The responses using direct numerical integration were presented using power spectral densities. In contrast to harmonic excitation, the amplitude of the response does not appear to approach that of the input. Instead, a higher effective cubic damping results in a higher vibration level of the isolated mass at frequencies below the resonance frequency. It also does not reduce explicitly the response amplitude around the resonance frequency unlike the linear viscous damping. For a constant displacement amplitude random excitation, the excitation frequency bandwidth is found to be a significant factor in the level of effective cubic damping. A broader excitation bandwidth results in a higher level of cubic damping force. The theoretical and numerical results for both harmonic and broadband excitation were validated experimentally. The experimental investigation was performed using a SDOF base excited vibration isolation system possessing a simple velocity feedback control active damper to reproduce the nonlinear damping force. The predictions were shown to be in good agreement with measurements thereby verifying the effects of cubic damping on a SDOF system undergoing harmonic and broadband base excitation.
18
Huang, Yao-Hsin. "Some fundamental issues of constrained layer damping treatments /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7046.
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Howard, Carl. "Active isolation of machinery vibration from flexible structures." Title page, abstract and table of contents only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phh8478.pdf.
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Thesis (Ph. D.)--University of Adelaide, Dept. of Mechanical Engineering, 1999?Copy 2 does not have a CD-ROM. Includes bibliographical references (p. 317-330). Also available in an electronic version.
20
Zhou, Li. "Vibration control of buildings using smart magnetorheological dampers /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202002%20ZHOU.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 163-177). Also available in electronic version. Access restricted to campus users.
21
Zhou, Shaoyi. "Advances in passive and active damping techniques." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI066.
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Les systèmes mécaniques (e.g. structures flexibles) sont généralement peu amortis, et par conséquent des vibrations de fortes amplitudes peuvent apparaitre. Il apparait nécessaire de développer des stratégies de contrôle vibratoire pour atténuer ces vibrations mécaniques. Cette thèse a pour objectif de développer plusieurs techniques d'amortissement de vibration passives ou actives. La première partie porte sur l'utilisation d'un “inerter” pour améliorer les performances de contrôle vibratoire de deux dispositifs existants, l'amortisseur à masse accordée (TMD) et deux TMDs placés en série (SDTMD). Dans le cas avec un TMD, on considère un système mécanique avec incertitudes ainsi que son optimisation H-infinity (worst-case optimization) en adoptant une approche purement algébrique. Dans le cas de SDTMD, on vise à contrôler la vibration d'un système déterministe. Son optimisation H-infinity s'effectue ici en utilisant une version étendue de la théorie de points fixes (FPT). Dans une seconde partie, on cherche à améliorer les performances de ce type de dispositif en positionnant un élément linéaire de raideur négative entre la base et la masse accordée. Deux cas d'étude sont menés: le TMD seul et celui basé sur l'inerter (IDVA). Les deux dispositifs ont une configuration non-traditionnelle, dont la masse accordée est liée à la base par l'intermédiaire d'un amortisseur visqueux ou un réseau mécanique basé sur l'inerter. La réalisation de ces dispositifs non-traditionnelles avec ou sans raideur négative et leurs shunts piézoélectriques sont étudiés et une analogie électromécanique est établie. Cette analogie permet d'étendre l'applicabilité des amortisseurs mécaniques et de faciliter les réglages. Dans la dernière partie, deux techniques d'amortissement actif et semi-actif sont développées. La première stratégie concerne une loi de contrôle hybride applicable au TMD et à l'IDVA. Le contrôleur proposé est composé d'un seul ou plusieurs compensateurs identiques, qui est caractérisé par un pôle à l'origine et deux zéros coïncidents réels. Les expressions analytiques sont développées dans les deux cas. La seconde technique de contrôle s'appuie sur l'atténuation de vibration par shunt électromagnétique (EMSD), pour laquelle aucun capteur est requis. Une inductance négative (NI) est employée dans les shunts électromagnétiques afin d'améliorer l'amortissement. Trois architectures possibles de NI dans un EMSD sont évaluées à travers le facteur de couplage électromécanique, qui quantifie l'efficacité de conversion énergétique entre les domaines mécanique et électrique. Finalement, six shunts électromagnétiques utilisant des NIs sont optimisés et analysésMechanical systems (e.g. flexible structures) are usually lightly damped so that they vibrate severally in response to dynamic loads. Therefore, vibration control strategies should be adopted in order to reduce the undesired vibration of mechanical systems. The objective of this thesis is to develop multiple vibration control techniques, which are either passive or active. The first part focuses on the application of inerter to enhance the vibration control performance of two existing control devices, the tuned mass damper (TMD) and the series double TMD (SDTMD). The inerter is employed to relate the tuned mass to the ground. In the case of TMD, a mechanical system under stiffness uncertainty is considered and the worst-case H-infinity optimization is addressed by means of an entirely algebraic approach. In the case of SDTMD, the vibration of a deterministic mechanical system is to be controlled and the H-infinity optimal design is carried out via an extended version of fixed points theory (FPT). Instead of using the inerter, the second part consists in improving the control effect by incorporating a linear negative stiffness between the ground and the tuned mass. Two case studies are conducted based on the non-traditional TMD and inerter-based dynamic vibration absorber (IDVA), whose tuned mass is related to the ground by a viscous damper or an inerter-based mechanical network, respectively. Later, the exact electrical realization of non-traditional configurations with or without negative stiffness is proposed, which is based on the piezoelectric transducer enclosed by a particular shunt circuit. This electromechanical analogy enables to extend the applicability of mechanical control devices and to facilitate the precise tuning. In the last part, active and semi-active vibration control techniques are developed. The first strategy consists in enhancing the control capability of passive TMD and IDVA by feeding back the displacement signal of mechanical system to the electromagnetic actuator. The proposed controller can be regarded as one or multiple basic units arranged in series, which is featured by one pole at the origin and two coalesced zeros on the real axis. Distinguished from the previous strategy, the semi-active control technique is based on electromagnetic shunt damping (EMSD), therefore, no additional sensor is required to measure the information of mechanical system. In order to artificially increase the shunt damping performance, the employment of negative inductance (NI) in the shunt circuit is considered. Three possible layouts of NI in the EMSD are assessed in terms of the electromechanical coupling factor, which quantifies the energy conversion efficiency between mechanical and electrical domains. Finally, six types of shunt circuits are optimally tuned according to the FPT and the beneficial effect of NI and the influence of its layout can be underlined
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Amos, Jay Max. "Torsional vibration characteristics of beams using viscoelastic damping treatment." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/19440.
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Ao, Wai Kei. "Electromagnetic damping for control of vibration in civil structures." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/31145.
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This thesis investigates an alternative solution to deal with the civil structure vibration. Non-contact electromagnetic or Eddy current damping is selected as a score of vibration suppression. Electromagnetic damping relies on the interaction between a permanent magnet and conductor. An electromagnetic damper (EMD) is applied both to a laboratory footbridge structure and 6-storey model-scale aluminium moment resisting frame (AMRF). In this first study the EMD is connected in series with an electronic shunt circuit to construct an electromagnetic shunt damper (EMSD). A robust optimisation method is applied to develop the corresponding optimal design formula of the EMSD. The principle of an EMSD is to convert mechanical energy to electrical energy. Hence, the induced electromotive force (emf) is generated by electromagnetic induction. This emf induces an amount of shunt damping, which is fedback to the structure to achieve vibration suppression. It was found that when the impedance was applied, the shunt damping feature was of a similar nature to viscous dampers. In contrast, when an RLC (resistance-inductance-capacitance) circuit is connected, the shunt damping is analogous to a tuned mass damper. A second form of EMD is Eddy current damper (ECD), which relies on a geometrical arrangement of permanent magnets and conductors to produce damping forces. The vertical and horizontal orientation of the magnet, unidirectional and alternative pole projection and moving different direction of the conductor are investigated. A theoretical study involving the infinite boundary and finite boundary (the method of images current) is carried out to obtain an analytical calculation of the damping force. On the basis of this analysis, one type of ECD prototype was physically built. A performance test was carried out to determine the damping characteristics of the ECD, which agreed with the results of the numerical analysis. In addition, the ECD was applied to control the dynamics of the 6-storey AMRF. It was found that, the ECD can effectively increase system damping and have a satisfactory control effect.
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Verdirame, Justin Matthew 1978. "Structural vibration damping using lightweight, low-wave-speed media." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40360.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 157-162).
Incorporation of a low-density, low-wave-speed medium (LWSM) into a structure yields significant damping if the speed of wave propagation in the medium is low enough for standing waves to arise in it. In this thesis, we characterize wave propagation in low-density granular media and foams for use as structural damping treatments and develop analytical and numerical techniques for prediction of the damping attained in structures that incorporate LWSM. Structural damping by incorporation of LWSM is attractive for hollow thin-walled structures. We develop analytical approximations for the loss-factor in the structural modes of cylindrical shells and Timoshenko beams and attain predictions in good agreement with measurements. For more complicated geometries, it is often necessary to employ a finite element model to predict the dynamics of structures. But inclusion of LWSM into a finite element model significantly increases the size of the model, introduces frequency-dependent material properties, and introduces a large number of modes that are dominated by deformation of the LWSM. Hence, the eigenvalue problem becomes significantly more difficult by addition of the LWSM.
(cont.) We develop an iterative approach based on the eigensolution of a structure without LWSM and the forced response of the LWSM to obtain approximations for the complex eigensolution. Damping by inclusion of LWSM is an attractive option for reduction of the sound radiated from vehicle driveshafts, which are typically thin-walled hollow cylinders with yokes welded at each end. The bending and ovaling modes of the driveshaft between 500 and 3000 Hz are efficient radiators of sound and are excited by gear transmission error in the rear differential. Filling the driveshaft with a. lossy, low-density foam adds significant damping to these modes and thus reduces the radiated sound.
by Justin Matthew Verdirame.
Ph.D.
25
SALLAM, MOHAMED ABDELGHANY. "Vibration Damping using Regenerative Suspensions for More Ecient Vehicles." Doctoral thesis, Politecnico di Torino, 2016. http://hdl.handle.net/11583/2643014.
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Vehicle vibration problem has been always an important area of research due to its negative effect on passenger comfort and vehicle safety. This problem can be solved partially by designing a good suspension system capable of maintaining an acceptable level of comfort and ensuring the vehicle safety on irregular roads. However, the conventional vehicle suspension dissipates the mechanical vibration energy in the form of heat which would waste a considerable amount of energy.
Regenerative shock absorber can capture the previously dissipated vibration energy and convert it to usable electrical energy for charging a battery or powering on-board electronic devices. Moreover, it can achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the oscillatory motion of the suspension system is employed to drive power generator.
However, the frequent bidirectional oscillation of the generator can cause a large impact force. This further leads to deteriorated energy harvesting performance, moving parts fatigue, and even system failure. In addition, the bidirectional oscillating motion will produce an irregular AC voltage. In order to charge batteries or power vehicle electronics, the voltage needs to be commutated with an electrical rectifier, in which the forward voltage of diodes unavoidably reduces the circuit’s efficiency.
As such, this thesis presents a study of an Electro-Hydrostatic Shock Absorber (EHSA) which can integrate the vibration damping and energy generation. The presented device consists of a modified twin-tube shock absorber with two check valves working as a hydraulic rectifier by which the bidirectional motion across the damper is converted to an asymmetric unidirectional rotation to drive the generator. The device has an advantage of having less number of check valves than the other counterpart devices which in turn would increase the overall efficiency of the system.
Following the system description, mathematical and numerical models have been developed to examine the response behavior of the regenerative shock absorber. Unlike the mathematical model in which some of the system dynamics were neglected, the numerical model took into consideration all the linear and non-linear elements of the presented device. For this purpose, Matlab's Simscape Toolbox has been used as an environment for multi-domain physical system.
The study is about the analysis of the performance of the electro-hydrostatic shock absorbers for automotive applications. The objective is to evaluate the fuel saving allowed by such solution. The study is performed by numerical analysis at different level of accuracy in two different configurations: with motion rectifier and without motion rectifier. The study evidences that both solutions have a promising potential of energy recuperation with a slight advantage of that with motion rectifier.
The results have shown that the developed regenerative shock absorber is capable of capturing a maximum of 24W average power with a maximum conversion efficiency of 42\% if the vehicle is going over a C-class road and when the load resistance is tuned to 2.6 Ohm. In case of using the device without motion rectifier, the average power is reduced to 22W with conversion efficiency of 38%. The carbon emissions that can be reduced by a car having this shock absorber can reach to 2.1 Gram of CO2 /km.
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Holdhusen, Mark Horner. "Experimental validation and the effect of damping on the state-switched absorber used for vibration control." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/16688.
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Young, Tyau-Her. "Extension of the Ritz method to the forced, damped vibrations of rotating structural elements /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487265555438797.
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Yellin, Jessica M. "An analytical and experimental analysis for a one-dimensional passive stand-off layer damping treatment /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/7030.
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Palmborg, John, and Hampus Söderman. "Vibration damping of alpine skis with implemented Flow Motion Technology." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263873.
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Flow Motion Technology AB has previously developed a technology to improve hockey skates and inlines. The technology called Flow Motion Technology (FMT) is utilizing the smooth and effective rolling motion of a human footstep, and has proven to be very successful after implementation in both hockey skates and inlines. Flow Motion Technology AB has interest in investigating whether the technology can be implemented in other sports applications, which this thesis project concerns. The project examines the implementation of FMT in the alpine skiing segment. The purpose is to provide Flow Motion Technology AB with a foundation for evaluating the potential of investing further in the development of FMT applied in alpine skiing. FMT is implemented in a feature positioned between ski and binding of most alpine race skis, commonly called a race plate. The work is divided into two parts; The first part covers the development and manufacturing of a prototype along with detailed description of the procedures and methods used. The second part is about the tests of the prototype’s vibration-damping properties carried out in laboratory environment along with analysis of the results. Initial field tests are also carried out followed by fundamental analysis. An existing plate intended for competition use is tested in parallel with the prototype and is used as a reference when analyzing the results. The results show that the ski equipped with the FMT plate dampened vibrations on an average of 27 % faster than the reference plate. Measurements was compiled for three damping intervals specified for the tests performed in laboratory. A statistically significant difference in all three cases was obtained. The measured maximum amplitude of the acceleration in the vibrations was also significantly lower for the ski implemented with the FMT plate compared to the reference plate. The eigen frequencies of the ski measured in laboratory were not significantly affected if the ski was fitted with the FMT plate or the reference plate. The eigen frequencies measured in field generally corresponded to the measured in laboratory, with the difference that they were offset on an average of 7 Hz higher in field.Flow Motion Technology AB har tidigare utvecklat en teknologi för att förbättra hockeyskridskor och inlines. Teknologin kallad Flow Motion Technology (FMT) utnyttjar den naturliga och effektiva rullande rörelse i en människas fotsteg, och har efter implementation i hockeyskridskor och inlines visat sig vara framgångsrik. Flow Motion Technology AB vill undersöka om denna teknologi kan implementeras i andra idrottssammanhang för att utvärdera möjligheter att bredda företagets affärsområde. Detta examensarbete är en del av denna undersökning, och i denna rapport beskrivs implementationen av FMT i segmentet alpinskidåkning. Syftet med projektet är att förse Flow Motion Technology AB med underlag för att utvärdera lönsamheten i att investera mer i utvecklingen av FMT riktad mot alpinskidåkning. FMT implementeras i projektet i en raceplatta, en komponent monterad mellan skida och bindning. Arbetet är uppdelat i två delar; utveckling och tillverkning av en funktionsprototyp med detaljerad beskrivning av tillvägagångssätt och metoder, samt tester av prototypens vibrationsdämpande prestanda i labbmiljö med tillhörande analys av resultat. Initiala tester utförs även i fält med enklare analys av resultat. En befintlig bindningsplatta avsedd för tävling testas parallellt med den utvecklade plattan och används som referens vid analys av resultaten. Resultaten visar att plattan implementerad med FMT dämpade en skidas vibrationer i genomsnitt 27 % snabbare än vad referensplattan gjorde vid de tre dämpningsintervall som specificerats för testen i labbmiljö. En statistiskt signifikant skillnad i alla tre fall. Den uppmätta maxamplituden för accelerationen i vibrationerna var även statistiskt signifikant lägre för skidan implementerad med FMT jämfört med referensplattan. Egenfrekvenserna uppmätta i labb påverkades inte nämnvärt om skidan var monterad med FMT-plattan eller referensplattan. De egenfrekvenser som uppmättes i fält motsvarade generellt de som uppmättes i labb med skillnaden att de var förskjutna till att i genomsnitt vara 7 Hz högre.
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Barsallo, Pacheco Nilma Rosa. "Material and Damping Characterization of Discretized Adhesive Tapes in Cantilever Beams undergoing Free and Forced Vibration." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/64357.
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The work is focused in investigating the effectiveness of discretized damping tapes applied to a cantilever beam subjected to free and forced vibrations. The work is divided into three main sections. First, we performed material characterization of the viscoelastic (VE) pressure sensitive adhesive layer of the damping tapes. To do so, we designed a novel quad shear specimen to measure shear storage and loss moduli, and tan delta from dynamic mechanical analyzer measurements. Second, the optimal discretization length for different damping tapes was experimentally determined and analytically verified using linear viscoelasticity and basic strength of materials and vibrations principles. These results showed a mean to improve the damping of a structure without increasing the weight of the added damping layer. Third, a nonlinear analysis was performed for cantilever beams with damping layers subjected to parametric excitation. Comparison of the response amplitude of the parametrically excited beam was performed for different discretization lengths, and system identification of the nonlinear parameters was carried out. The effects of large deflections of a beam under parametric excitation were analyzed; large deflections were found to induce localized buckling of the stiff constraining layer of the damping tape that would invalidate some of the assumptions and analytical solutions that do not take such phenomena into account.Master of Science
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Wang, Zhen. "Enhanced self-powered vibration damping of smart structures by modal energy transfer." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0067/document.
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Le travail de cette thèse propose une nouvelle méthode de contrôle appelée SSDH (Synchronized Switch Damping and Harvesting) basée sur l’idée de redistribution de l’énergie récupérée pour réduire l’énergie vibratoire d’une structure. De nombreuses recherches ont concerné le contrôle de vibration des structures souples. L’utilisation de l’approche modale pour ce genre de structure présente de nombreux intérêts. Dans le cadre de cette thèse l’idée est de récupérer l’énergie des modes qui ne sont pas contrôlés de façon à améliorer l’effet d’amortissement des modes ciblés par le contrôle sur une même structure. Pour cela, sur la base de la technique semi-active de contrôle, un circuit de contrôle modal a été conçu pour être compatible, via un convertisseur, avec des techniques semi-active de récupération d’énergie qui ont elles même été adaptées en modal. Plusieurs variantes de la méthode SSDH ont été testées en simulation. De façon à estimer l’efficacité du concept, une application sur un modèle expérimental d’une smart structure simple est proposée. Actionneurs et capteurs utilisent des matériaux piézoélectriques qui présentent les effets directs et inverses utiles pour la récupération d’énergie et le contrôle vibratoire. Après optimisation des différents paramètres électromécaniques et électriques, les résultats des simulations menées sous excitations bisinusoidale ou en bruit blanc, montrent que la nouvelle méthode de contrôle autoalimentée SSDH est efficace et robuste. Elle améliore sensiblement l’amortissement produit par les techniques semi-actives modales de base (SSDI) grâce à l’utilisation de l’énergie modale récupéréeIn a context of embedded structures, the next challenge is to develop an efficient, energetically autonomous vibration control technique. Synchronized Switch Damping techniques (SSD) have been demonstrated interesting properties in vibration control with a low power consumption. For compliant or soft smart structures, modal control is a promising way as specific modes can be targetted. This Ph-D work examines a novel energy transfer concept and design of simultaneous energy harvesting and vibration control on the same host structure. The basic idea is that the structure is able to extract modal energy from the chosen modes, and utilize this harvested energy to suppress the target modes via modal control method. We propose here a new technique to enhance the classic SSD circuit due to energy harvesting and energy transfer. Our architecture called Modal Synchronized Switching Damping and Harvesting (Modal SSDH) is composed of a harvesting circuit (Synchronized Switch Harvesting on Inductor SSHI), a Buck-Boost converter and a vibration modal control circuit (SSD). Various alternatives of our SSDH techniques were proposed and simulated. A real smart structure is modeled and used as specific case to test the efficiency of our concept. Piezoelectric sensors and actuators are taken as active transducers, as they develop the direct and inverse effects useful for the energy harvesting and the vibration damping. Optimization are running out and the basic design factors are discussed in terms of energy transfer. Simulations, carried out under bi-harmonic and noise excitation, underline that our new SSDH concept is efficient and robust. Our technique improve the damping effect of semi-active method compared to classic SSD method thanks to the use of harvested modal energy
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Lane, Jeffrey Scott. "Control of dynamic systems using semi-active friction damping." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/16020.
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Jones, Janeen Ayana. "Modal analysis on a stiffened panel : an application of laser vibrometry." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16397.
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Li, Kaixiang. "Structural vibration damping with synchronized energy transfer between piezoelectric patches." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00735788.
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Advanced materials such as carbon fiber, composite materials et al. are more and more used in modern industry. They make the structures lighter and stiffer. However, they bring vibration problems. Researchers studied numerous methods to eliminate the undesirable vibrations. These treatments are expected to be a compact, light, intellectual and modular system. Recently, a nonlinear technique which is known as Synchronized Switch Damping (SSD) technique was proposed. These techniques synchronously switched when structure got to its displacement extremes that leading to a nonlinear voltage on the piezoelectric elements. This resulting voltage showed a time lag with the piezoelectric strain thus causing energy dissipation. Based on the developed SSD techniques, a new synchronized switch damping e.g. Synchronized Switch Damping with Energy Transfer (SSDET) was proposed in this document. This method damped the vibration by using the energy from other vibrating form. The objectives of the work reported in this document were threefold. The first one consisted of introduction of SSDET principle and developing its control law. This part aimed at establishing the mathematical model and verifying the proposed method by mathematical tools. Then, the experimental validations were carried out. Three experiments with different configurations demonstrated that SSDET can be implemented not only between structures but also vibrating modes in one structure. A SSDET scheme with multi-patches was also investigated for improving the damping. Finally, a bidirectional SSDET concept was introduced based on the original SSDET technique. This technique be regarded as a multimode control SSDET. Since it privileged the target vibration while keeps a decent control effect on the source vibration.
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De, Marneffe Bruno. "Active and passive vibration isolation and damping via shunted transducers." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210613.
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Many different active control techniques can be used to control the vibrations of a mechanical structure: they however require at least a sensitive signal amplifier (for the sensor), a power amplifier (for the actuator) and an analog or digital filter (for the controller). The use of all these electronic devices may be impractical in many applications and has motivated the use of the so-called shunt circuits, in which an electrical circuit is directly connected to a transducer embedded in the structure. The transducer acts as an energy converter: it transforms mechanical (vibrational) energy into electrical energy, which is in turn dissipated in the shunt circuit. No separate sensor is required, and only one, generally simple electronic circuit is used. The stability of the shunted structure is guaranteed if the electric circuit is passive, i.e. if it is made of passive components such as resistors and inductors.
This thesis compares the performances of the electric shunt circuits with those of classical active control systems. It successively considers the use of piezoelectric transducers and that of electromagnetic (moving-coil) transducers.
In a first part, the different damping techniques are applied on a benchmark truss structure equipped with a piezoelectric stack transducer. A unified formulation is found and experimentally verified for an active control law, the Integral Force Feedback (IFF), and for various passive shunt circuits (resistive and resistive-inductive). The use of an active shunt, namely the negative capacitance, is also investigated in detail. Two different implementations are discussed: they are shown to have very different stability limits and performances.
In a second part, vibration isolation with electromagnetic (moving-coil) transducers is introduced. The effects of an inductive-resistive shunt circuit are studied in detail; an equivalent mechanical representation is found. The performances are compared with that of resonant shunts and with that of active isolation with IFF. Next, the construction of a six-axis isolator based on a Stewart Platform is presented: the key parameters and the main limitations of the system are highlighted.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Bhaskar, Atul. "Damping in mechanical vibration : new methods of analysis and estimation." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314853.
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Liu, Yuyou. "Semi-active damping control for vibration isolation of base disturbances." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/66164/.
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This thesis is concerned with semi-active damping control for vibration isolation of base disturbances. The aim is to investigate the effectiveness and suitability of semi-active damping control strategies for improving steady-state vibration isolation. A single-degree-of-freedom (SDOF) system, comprising a semi-active damper with a linear passive spring in parallel, is used to study the vibration isolation of base excitation. The semi-active control strategies investigated include on-off skyhook control, continuous skyhook control, on-off balance control and continuous balance control. Chatter and jerk problems are investigated, which can arise in numerical simulations and possibly in practice when using semi-active control strategies. Anti-chatter and anti-jerk control strategies are proposed. These control strategies are implemented numerically in Matlab/Simulink. Harmonic, periodic and random disturbances are considered in this thesis. The vibration isolation performance is evaluated in terms of Root-Mean-Square (RMS) acceleration transmissibility. The performance of these control strategies for the isolation of harmonic disturbances is firstly studied. The performance is compared with those of an adaptive-passive control strategy, a conventional and a skyhook passive damper. Results show that the semi-active control strategies can provide a better isolation than a conventional passive system with an equivalent damping level. The semi-active damper can provide isolation over the whole frequency range if the on-state damping of the semi-active damper is big enough. The fraction of time when the damper is turned on or off is found to be frequency dependent. The effects of secondary frequency, which is a harmonic or subharmonic of the fundamental frequency on switching time of the semi-active damper for isolation of the primary harmonic are examined. Upper bounds are derived for fraction of time when the switching time for the fundamental frequency may be affected by the presence of a secondary frequency. The performance of the semi-active isolation system for periodic and random disturbances, where there is more than one harmonic in the disturbance spectrum is investigated. The results for square wave and triangular wave disturbances suggest that semi-active control strategies are promising for periodic disturbance. Three special cases are considered for random disturbances when the acceleration, velocity and displacement inputs have flat spectra. The semi-active control strategies can provide some advantage in performance for random velocity and displacement disturbances with medium to high damping ratios. Only continuous skyhook control strategy can provide some benefit in isolation performance for random acceleration disturbances. Following on from the numerical simulations, experimental work is carried out to validate the simulation results. The experimental set-up incorporates an electromagnetic device as a semi-active damper. The on-off skyhook control algorithm is chosen to be implemented using an analogue circuit. The damping of the electromagnetic semi-active damper is achieved by opening and closing the magnet-coil circuit. Numerical predictions are confirmed by experimental observation. The performance of the electromagnetic damper is limited by the achievable damping level.
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Cahill, John J. "Experimental studies of noise/vibration damping for undersea warfare applications." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FCahill.pdf.
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Marhadi, Kun Saptohartyadi. "Particle impact damping: influence of material and size." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1459.
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In this study, particle impact damping is measured for a cantilever beam with a particle-filled enclosure attached to its free end. Many particle materials are tested: lead spheres, steel spheres, glass spheres, tungsten carbide pellets, lead dust, steel dust, and sand. The effects of particle size are also investigated. Particle diameters are varied from about 0.2 mm to 3 mm. The experimental data collected is offered as a resourceful database for future development of an analytical model of particle impact damping.
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Stasolla, Vincenzo. "Numerical analysis of aerodynamic damping in a transonic compressor." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264359.
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Aeromechanics is one of the main limitations for more efficient, lighter, cheaper and reliable turbomachines, such as steam or gas turbines, as well as compressors and fans. In fact, aircraft engines designed in the last few years feature more slender, thinner and more highly loaded blades, but this trend gives rise to increased sensitivity for vibrations induced by the fluid and result in increasing challenges regarding structural integrity of the engine. Forced vibration as well as flutter failures need to be carefully avoided and an important parameter predicting instabilities in both cases is the aerodynamic damping. The aim of the present project is to numerically investigate aerodynamic damping in the first rotor of a transonic compressor (VINK6). The transonic flow field leads to a bow shock at each blade leading edge, which propagates to the suction side of the adjacent blade. This, along with the fact that the rotating blade row vibrates in different mode shapes and this induces unsteady pressure fluctuations, suggests to evaluate unsteady flow field solutions for different cases. In particular, the work focuses on the unsteady aerodynamic damping prediction for the first six mode shapes. The aerodynamic coupling between the blades of this rotor is estimated by employing a transient blade row model set in blade flutter case. The commercial CFD code used for these investigations is ANSYS CFX. Aerodynamic damping is evaluated on the basis of the Energy Method, which allows to calculate the logarithmic decrement employed as a stability parameter in this study. The least logarithmic decrement values for each mode shape are better investigated by finding the unsteady pressure distribution at different span locations, indication of the generalized force of the blade surface and the local work distribution, useful to get insights into the coupling between displacements and consequent generated unsteady pressure. Two different transient methods (Time Integration and Harmonic Balance) are employed showing the same trend of the quantities under consideration with similar computational effort. The first mode is the only one with a flutter risk, while the higher modes feature higher reduced frequencies, out from the critical range found in literature. Unsteady pressure for all the modes is quite comparable at higher span locations, where the largest displacements are prescribed, while at mid-span less comparable values are found due to different amplitude and direction of the mode shape. SST turbulence model is analyzed, which does not influence in significant manner the predictions in this case, with respect to the k-epsilon model employed for the whole work. Unsteady pressure predictions based on the Fourier transformation are validated with MATLAB codes making use of Fast Fourier Transform in order to ensure the goodness of CFX computations. Convergence level and discrepancy in aerodamping values are stated for each result and this allows to estimate the computational effort for every simulation and the permanent presence of numerical propagation errors.Aeromekanik är en av huvudbegränsningarna för mer effektiva, lättare, billigare och mer pålitliga turbomaskiner, som ångturbiner, gasturbiner, samt kompressorer och fläktar. I själva verket har flygplansmotorer som designats under de senaste åren har fått tunnare och mer belastade skovlar, men denna trend ger upphov till ökad känslighet för aeromekaniska vibrationer och resulterar i ökande utmaningar när det gäller motorns strukturella integritet. Aerodynamiskt påtvingade vibrationer såväl som fladder måste predikteras noggrant för att kunna undvikas och en viktig parameter som förutsäger instabilitet i båda fallen är den aerodynamiska dämpningen. Syftet med det aktuella projektet är att numeriskt undersöka aerodynamisk dämpning i den första rotorn hos en transonisk kompressor (VINK6). Det transoniska flödesfältet leder till en bågformad stötvåg vid bladets främre kant, som sprider sig till sugsidan på det intilliggande bladet. I och med detta, tillsammans med det faktum att den roterande bladraden vibrerar i olika modformer och detta inducerar instationära tryckfluktuationer, syftar detta arbete på att utvärdera flödesfältslösningar för olika fal. I synnerhet fokuserar arbetet på prediktering av den instationära aerodynamiska dämpningen för de första sex modformen. Den aerodynamiska kopplingen mellan bladen hos denna rotor uppskattas genom att använda en transient bladradmodell uppsatt för fladderberäkningen. Den kommersiella CFD-koden som används för denna utredning är ANSYS CFX. Aerodynamisk dämpning utvärderas med hjälp av energimetoden, som gör det möjligt att beräkna den logaritmiska minskningen som används som en stabilitetsparameter i denna studie. De minsta logaritmiska dekrementvärdena för varje modform undersöks bättre genom att hitta den ostadiga tryckfördelningen på olika spannpositioner, som är en indikering av den lokala arbetsfördelningen, användbar för att få insikt i kopplingen mellan förskjutningar och därmed genererat ostabilt tryck. Två olika transienta metoder används som visar samma trend för de kvantiteter som beaktas med liknande beräkningsinsatser. Den första modformen är den enda med en fladderrisk, medan de högre modformerna har högre reducerade frekvenser, och ligger utanför det kritiska intervallet som finns i litteraturen. Instationärt tryck för alla moder är ganska jämförbart på de högre spannpositioner, där de största förskjutningarna föreskrivs, medan runt midspannet finns mindre jämförbara värden på grund av olika amplitud och riktning för modformen. SSTturbulensmodellen analyseras, som i detta fall inte påverkar predikteringen på ett betydande sätt. Det predikterade instationära trycket baserad på Fourier-transformationen valideras med MATLAB-koder som använder sig av Fast Fourier Transform för att säkerställa noggrannheten hos CFX-beräkningar. Konvergensnivå och skillnader i aerodämpningsvärden anges för varje resultat och detta gör det möjligt att uppskatta beräkningsinsatsen för varje simulering och uppskatta utbredningen av det numeriska felet.
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Carey, Agustin E. "Experimental studies of welding effects on damping for undersea warfare applications." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FCarey.pdf.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2002.Thesis advisor(s): Young W. Kwon, Young S. Shin. Includes bibliographical references (p. 51). Also available online.
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Gonsalves, Diane Helen. "Chaos concepts in mechanical systems with clearances." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387216.
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This thesis considers the use of chaos concepts in investigating the dynamics of two discontinuously nonlinear mechanical systems having two degrees of freedom. The nonlinearity considered is in the form of a discontinuous stiffness effect, and can cause the systems to exhibit chaotic motion. The first system is a rotor system with a bearing clearance effect. The second is a nonlinear vibration absorber, comprising a conventional linear absorber and a linear snubber stiffness, which the auxiliary mass intermittently contacts. Numerical integration is used in solving the equations of motion for each system. Equivalent physical rigs are tested. Both the theoretical and experimental results are analysed using chaos techniques such as phase plane portraits, Poincaré maps, frequency spectra and bifurcation diagrams. Comparison made between the differently acquired results shows that fairly good correlation is obtained in both systems, for realistic values of damping. Periodic, quasiperiodic and chaotic responses are exhibited by both systems, for different combinations of system parameters, with the responses of the systems being extremely sensitive to changes in these parameters. Investigations of the rotor system concluded that quasi-periodic responses are only possible if there is some form of cross-coupling present. An effective discontinuously nonlinear absorber is developed, theoretically. A reduction in the amplitude of the second resonance peak of the linear absorber is achieved. This enables the primary system to be operated over a wider frequency range without reaching the large amplitudes to the second resonance. The non-linear absorber also has the effect of attenuating the response from the auxiliary mass. Fatigue analysis is carried out to investigate the effect of chaotic motions on mechanical components. The analysis reveals the subharmonic motions are more damaging than chaotic motions, which are in turn more damaging than simple fundamental responses.
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Li, Zhuang. "Vibration and acoustical properties of sandwich composite materials /." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Dissertation/LI_ZHUANG_26.pdf.
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Fortgang, Joel D. "Concurrent design of input shaping and vibration absorbers." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17130.
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Kyriazoglou, Christos. "Development of vibration damping for structural integrity assessment of composite laminates." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288227.
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Wu, Dan. "Piezoelective semi-active networks for structural vibration damping with energy redistribution." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0078/document.
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Le contrôle des vibrations est devenu un enjeu majeur et a reçu une attention considérable dans de nombreuses applications industrielles. Diverses approches de recherche ont été exploitées pour réduire les vibrations indésirables. Les matériaux intelligents développés peuvent contrôler et supprimer les vibrations d'une manière efficace et intelligente avec un poids ajouté supplémentaire négligeable par rapport au système. La majorité des recherches sur les matériaux intelligents a mis l'accent sur le contrôle d’une structure composite constituée avec des transducteurs piézoélectriques intégrés ou liés à la structure. Les avantages des matériaux piézoélectriques sont une bande passante élevée, une grande compacité, leur légèreté, leur facilité de mise en œuvre et les leurs bonnes caractéristiques de couplage électromécanique, ce qui les rend appropriés en tant que actionneurs et capteurs. Récemment, une technique de contrôle de vibration semi-passif non linéaire, appelé SSD (Synchronized Switch Damping) a été développée. SSD s'appuie sur une élévation cumulative de la tension aux bonnes de l’élément piézoélectrique résultant de la commutation continue de ladite tension. Il a été montré que les performances d’amortissement sont fortement liées à cette amplitude de tension totale disponible. Basé sur les techniques SSD, une nouvelle approche globale pour l'amortissement des vibrations d’une structure “intelligente” est proposée dans cette thèse. Elle est fondée sur une redistribution modale d'énergie par l'intermédiaire d'un réseau d'éléments piézoélectriques. L'objectif de ce travail est d’augmenter la tension piézo-électrique (directement lié à l'énergie opératoire d’amortissement) pour l'amélioration les performances d'amortissement. Dans cette approche semi-active proposée, l'énergie supplémentaire est fournie par un réseau d'éléments piézoélectriques qui recueille cette énergie sur les différents modes de vibration de la structure. Deux topologies de réseau d'origine sont développées pour le transfert d’énergie. L’une s'appelle SSDT "Synchronized Switch Damping by energy Transfer". L’autre est définie comme SSDD "Synchronized Switch Damping with Diode". L’évaluation et la comparaison des performances sont effectuées sur un modèle représentatif d'une plaque encastrée équipée de plusieurs éléments piézoélectriques dans le cas d’une excitation multimodale. Par rapport à la méthode SSDI modale, des résultats de simulation et un modèle global théorique sont enfin proposés pour démontrer la relation entre l'amélioration d’amortissement réalisable et l'énergie transférée par rapport à l'énergie mécanique de la structure. Ces résultats prouvent la capacité d'un réseau d'éléments piézoélectriques dans la gestion et la redistribution d'énergie de la structure pour améliorer l'amortissement de vibrations d’une structure intelligenteStructural vibration control is an important issue and has received considerable research attention in many industry applications. Researches investigated various approaches to reduce undesirable vibrations. The smart materials can control and suppress vibration in an efficient and “intelligent” way without causing much additional weight. The majority of research in smart damping materials has focused on the control of composite structure using embedded or bonded piezoelectric transducers. The advantages of piezoelectric materials include high achievable bandwidth, compactness, lightness, easy implementation and good electromechanical coupling characteristics, thus making them appropriate for actuators and sensors applications. Recently, a non-linear semi-passive vibration control technique, so-called Synchronized Switch Damping (SSD), has been developed. SSD technique relies on a cumulative build-up of the voltage resulting from the continuous switching of the piezoelectric voltage and it was shown that the performance is strongly related to this total voltage amplitude available. Based on SSD techniques, a new global approach for improved vibration damping of smart structure, based on global energy redistribution by means of a network of piezoelectric elements is proposed in this thesis. The objective of this work is to propose a new approach to increase the piezoelectric voltage (also related to the damping operative energy) in order to improve the damping performance. In the proposed semi-active approach, the extra energy used to improve this voltage is gathered on the various modes of the structure using an interconnected piezoelectric element network. Two original network topologies are developed for transferring energy. One is named SSDT for “Synchronized Switch Damping by energy Transfer”. The second is defined as SSDD for “Synchronized Switch Damping with Diode”. Performance evaluations and comparisons are performed on a model representative of a clamped plate equipped with piezoelectric elements in the case of multimodal motion. Compared to the Modal-SSDI method used as a baseline, simulation results and a global theoretical model are proposed demonstrating the relationship between the achievable damping improvement and the ratio of transferred energy to the structure mechanical energy, thus proving the capability of a network of piezoelectric elements for global energy management and redistribution in order to improve the vibration damping of smart structures
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Kakou, Paul-Camille. "Towards A Mobile Damping Robot For Vibration Reduction of Power Lines." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103374.
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As power demand across communities increases, focus has been given to the maintenance of power lines against harsh environments such as wind-induced vibration (WIV). Currently, Inspection robots are used for maintenance efforts while fixed tuned mass dampers (FTMDs) are used to prevent structural damages. However, both solutions are facing many challenges. Inspection robots are limited by their size and considerable power demand, while FTMDs are narrowband and unable to adapt to changing wind characteristics, and thus are unable to reposition themselves at the antinodes of the vibrating loop. In view of these shortcomings, we propose a mobile damping robot (MDR) that integrates inspection robots' mobility and FTMDs WIV vibration control to help maintain power lines. In this effort, we model the conductor and the MDR by using Hamilton's principle and we consider the two-way nonlinear interaction between the MDR and the cable. The MDR is driven by a Proportional-Derivative controller to the optimal vibration location (i.e, antinodes) as the wind characteristics vary. The numerical simulations suggest that the MDR outperforms FTMDs for vibration mitigation. Furthermore, the key parameters that influence the performance of the MDR are identified through a parametric study. The findings could set up a platform to design a prototype and experimentally evaluate the performance of the MDR.Master of Science
Power lines are civil structures that span more than 160000 miles across the United States. They help electrify businesses, factories and homes. However, power lines are subject to harsh environments with strong winds, which can cause Aeolian vibration. Vibration in this context corresponds to the oscillation of power lines in response to the wind. Aeolian vibration can cause significant structural damages that impact public safety and result in a significant economic loss. Today, different solutions have been explored to limit the damages to these key structures. For example, the lines are commonly inspected by foot patrol, helicopters, or inspection robots. These inspection techniques are labor intensive and expensive. Furthermore, Stockbridge dampers, mechanical vibration devices, can be used to reduce the vibration of the power line. However, Stockbridge dampers can get stuck at location called nodes, where they have zero efficiency. To tackle this issue, we propose a mobile damping robot that can re-adjust itself to points of maximum vibration to maximize vibration reduction. In this thesis, we explore the potential of this proposed solution and draw some conclusions of the numerical simulations.
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Ping, Hsin-Chih. "Passive vibration control of thick aluminum plates using viscoelastic layered damping." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA243990.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 1990.Thesis Advisor(s): Shin, Y.S. ; Kim, K.S. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Identifier(s): Acoustics, damping, ship silencing, MSE (modal strain energy), constrained viscoeleastic layer method, aluminum plates, milled pocket plate, floating element plate. Author(s) subject terms: Vibration, damping, viscoelastic material, constrained layer damping. Includes bibliographical references (p. 149). Also available in print.
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Lossouarn, Boris. "Multimodal vibration damping of structures coupled to their analogous piezoelectric networks." Thesis, Paris, CNAM, 2016. http://www.theses.fr/2016CNAM1062/document.
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L'amplitude vibratoire d'une structure mince peut être réduite grâce au couplage électromécanique qu'offrent les matériaux piézoélectriques. En termes d'amortissement passif, les shunts piézoélectriques permettent une conversion de l'énergie vibratoire en énergie électrique. La présence d'une inductance dans le circuit crée une résonance électrique due à l'échange de charges avec la capacité piézoélectrique. Ainsi, l'ajustement de la fréquence propre de ce shunt résonant à celle de la structure mécanique équivaut à la mise en œuvre d'un amortisseur à masse accordée. Cette stratégie est étendue au contrôle d'une structure multimodale par multiplication du nombre de patchs piézoélectriques. Ceux-ci sont interconnectés via un réseau électrique ayant un comportement modal approximant celui de la structure à contrôler. Ce réseau multi-résonant permet donc le contrôle simultané de plusieurs modes mécaniques. La topologie électrique adéquate est obtenue par discrétisation de la structure mécanique puis par analogie électromécanique directe. Le réseau analogue fait apparaître des inductances et des transformateurs dont le nombre et les valeurs sont choisis en fonction de la bande de fréquences à contrôler. Après s'être penché sur la conception de composants magnétique adaptés, la solution de contrôle passif est appliquée à l'amortissement de structures unidimensionnelles de type barres ou poutres. La stratégie est ensuite étendue au contrôle de plaques minces par mise en œuvre d'un réseau électrique bidimensionnelStructural vibrations can be reduced by benefiting from the electromechanical coupling that is offered by piezoelectric materials. In terms of passive damping, piezoelectric shunts allow converting the vibration energy into electrical energy. Adding an inductor in the circuit creates an electrical resonance due to the charge exchanges with the piezoelectric capacitance. By tuning the resonance of the shunt to the natural frequency of the mechanical structure, the equivalent of a tuned mass damper is implemented. This strategy is extended to the control of a multimodal structure by increasing the number of piezoelectric patches. These are interconnected through an electrical network offering modal properties that approximate the behavior of the structure to control. This multi-resonant network allows the simultaneous control of multiple mechanical modes. An adequate electrical topology is obtained by discretizing the mechanical structure and applying the direct electromechanical analogy. The analogous network shows inductors and transformers, whose numbers and values are chosen according to the frequency band of interest. After focusing on the design of suitable magnetic components, the passive control strategy is applied to the damping of one-dimensional structures as bars or beams. It is then extended to the control of thin plates by implementing a two-dimensional analogous network
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Rafique, Sajid. "Piezoelectric vibration energy harvesting and its application to vibration control." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/piezoelectric-vibration-energy-harvesting-and-its-application-to-vibration-control(d9edcedf-054e-4921-9ba3-5e015b9bbd8f).html.
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Vibration-based energy harvesting using piezoelectric materials have been investigated by several research groups with the aim of harvesting maximum energy and providing power to low-powered wireless electronic systems for their entire operational life. The electromechanical coupling effect introduced by the piezoelectric vibration energy harvesting (PVEH) mechanism presents modelling challenges. For this reason, there has been a continuous effort to develop different modelling techniques to describe the PVEH mechanism and its effects on the dynamics of the system. The overall aims of this thesis are twofold: (1) a thorough theoretical and experimental analysis of a PVEH beam or assembly of beams; (2) an in-depth analytical and experimental investigation of the novel concept of a dual function piezoelectric vibration energy harvester beam/tuned vibration absorber (PVEH/TVA) or 'electromechanical TVA' and its potential application to vibration control. The salient novel contributions of this thesis can be summarised as follows: (i) An in-depth experimental validation of a PVEH beam model based on the analytical modal analysis method (AMAM), with the investigations conducted over a wider frequency range than previously tested. (ii) The precise identification of the electrical loads that harvest maximum power and that induce maximum electrical damping. (iii) A thorough investigation of the influence of mechanical damping on PVEH beams. (iv) A procedure for the exact modelling of PVEH beams, and assemblies of such beams, using the dynamic stiffness matrix (DSM) method. (v) A procedure to enhance the power output from a PVEH beam through the application of a tip rotational restraint and the use of segmented electrodes. (vi) The theoretical basis for the novel concept of a dual function PVEH beam/TVA, and its realisation and experimental validation for a prototype device. A thorough experimental validation of a cantilever piezoelectric bimorph energy harvester without a tip mass is presented under random excitation. The study provided a deep insight into the effect of PVEH on the dynamics of the system for variations in electrical load. An alternative modelling technique to AMAM, based on the DSM, is introduced for PVEH beams. Unlike AMAM, the DSM is exact, since it is based on the exact solution to the bending wave equation. It also readily lends itself to the modelling of beams with different boundary conditions or assemblies of beams of different crosssections. AMAM is shown to converge to DSM if a sufficiency of modes is used. Finally, an in-depth theoretical and experimental investigation of a prototype PVEHbeam/TVA device is presented. This device comprises a pair of bimorphs shunted by R-L-C circuitry and can be used as a tuned mass damper (TMD) to attenuate a vibration mode of a generic structure. The optimal damping required by this TMD is generated by the PVEH effect of the bimorphs. Such a device combines the advantages of conventional mechanical and electrical TVAs, overcoming their relative disadvantages. The results demonstrate that the ideal degree of attenuation can be achieved by the proposed device through appropriate tuning of the circuitry, thereby presenting the prospect of a novel class of 'electromechanical' tuned vibration absorbers.